Originally Posted by Blogwitch
I see you have hit the steam everywhere barrier usually associated with the open faced turbines, imagine that in an enclosed hull, it is like emptying your boiler directly into the hull, it would be water swamped in no time.
That is why on my second unit (3 rotor) I put a collection chamber on it to send any exhaust overboard.
John, this was a test running the turbine hence i had not completed the steamturbine with the cover + exhaust pipe to lead steam out of the boat.
John wrote: The vid show it running on air, but it has run on steam, and the collector worked very well indeed, but my 3.5" diameter gas fired boiler just couldn't keep up with it's requirements, I had to keep stopping to allow the pressure to build up again.
---> Replace with a smaller orifice (steam jet) to prevent loss of pressure in the steam boiler and keep steam turbine running. As rule the steam turbine need a big heat of surface in the boiler or use flash boiler.
My own experience: Do not use too large turbine diameter as it requires higher vapor pressure and greater consumption. With a turbine diameter 30-35 mm will provide higher speed than a large turbine diameter. The turbine should act as flywheels as being high torque. The turbine wheel should have more turbine blades to keep steady power from the steam jet. Use ball bearings to keep the friction low as possible. Oil viscosity is critical in relation to the vapor pressure vs. speed.
I took the test with difference oils in the bearings.
Here are the tests of oils and measured revolutions per minute:
Work pressure= Mobil ESP 5W-30 / Air tool oil / Diesel oil (fuel for diesel engine as lubricant)
1 bar= 4700 / 13230 / 17600
1.5 bar= 6200 / 17900 / 25700
2 bar= 11400 / 21660 / 31500
2.5 bar= 15500/26340 / 36700
3 bar= 18600 / 28800 / 41800
As i can see the ball bearing get less friction with diesel oil as lucricant, it is sensitive for jet stream from nozzle. With high revolution above 15000, i can feel there are enough torque when trying to stop the turbine shaft.